Customer AS

Sean Donelain wrote:

PS There is a proof by existance that reliable operation w/o
  customer multihoming is possible. It is called POTS.

That's funny. Anyone who needs reliable telephone service
quickly learns how to multi-home between telephone providers,
inbound and outbound.

Inbound? Huh? Just dial a different number?

AT&T periodically puts out a press release
saying their network is so reliable, no one needs to buy service
from anyone else.

No matter what, POTS is a lot more reliable and dependable than
Internet. That definitely can be attributed by adequate resources
being spent on the redundancy.

Anyone who needs reliable electrical service, quickly learns
how to multi-home between electrical providers. The street
mains, a UPS, and generator. Some people even get a redundant
connection to another street mains.

Ah, if onle one could store Internet connectivity in a battery.

Yes, it is complicated to multi-home between providers of
anything (telphone, electricity, Internet, bagels).

Not at all. Everything you can store (like bagels) is easy.

A redundant connection to the same provider might help in a few limited

In about 98% of all cases of equipment malfunction.

But generally, when a provider fails on one
connection, the probility their other connections are working
drop dramatically.

Ghm. What makes you think it does not drop nearly as much
for inter-provider multihoming?

When the electricity fails, using a different
connection to the same electical provider usually doesn't work

Or, as recent intertie problems showed, connection to any provider
whatsoever also doesn't work. If you don't drag wires to the
other coast, that's it.

That's why people buy UPS's instead of second power supplies.

The person who would invent an "Uninterruptible Network Supply"
is going to be filthy rich.

The question about multihoming is easy -- what is price/benefits?
"Price" includes price for society at large, as well.


PS. An often forgotten fact from the life of fault-tolerant

  Practically all systems have threshold where addition
  of extra redundancy actually makes system less reliable!

  That is because the probability of Bysantine-type
  failures (i.e. ones which are not adequately dealt with
  by means of replication, something like cascading power
  failures, or bogus routes) grows with the number of
  components (at least linearly), and the benefits of
  redundancy diminish as negative exponent.

  BTW, Internet is way beyond the threshold if you look at
  it as a system. Therefore everything which makes the
  network simplier improves its reliablity.